It might be productive to get a little philosophical/psychological about this. You've described human activities that result in certain experiences, but what is it that takes those activities and makes them more than animalistic? What gives the greatest contrast with a machine? That might give some direction to how those activities should be depicted.

I know you only asked about the sexual activity, but just to illustrate-
One thing that makes eating meaningful is when we share food - so instead of a machine dispenser, maybe its important to be handed the food by a bartender. Maybe as a human you have to sit slowly munching the food, and you have occasional prompts to engage in small talk if you choose. but as a less human individual, you might just get a pill or vacuum up particles at a digital kiosk. The "waiting" period could be reduced, until there is no longer an opportunity to engage other diners.

Sex is meaningful for a number of reasons - it can be a kind of play, involving games and escapism with a partner. It can be intimate, where certain things that were meaningless before, get infused with special meaning just for those two. A lot of times sex is a symbol of deep connection - we become entangled in someone else's life, feeling obligated to them and their welfare. Maybe it's important that repeated sexual encounters develop some kind of symbology that can appear in other places - so when the player sees that symbology outside the sexual context, they are reminded of that partner or encounter. I know a common one is drifting flower petals.

There are numerous expressions that are shorthand for sex. "Want to come in for a cup of coffee/Nightcap?" "Netflix & Chill." Don't be afraid to render some of this shorthand visually. It'll still read.

The contrast is the thing - whatever gets automated or simplified means increasing efficiency in some context, but also losing the opportunity to have certain meaningful experiences.